The project will define the distribution of contractile proteins malignant melanocytes migrating in the radial growth phase (RGP) and vertical growth phase (VGP) of human primary cutaneous malignant melanoma as contrasted with nevus cell precursor lesions (dysplastic nevi) and benign nevocellular nevi and metastatic lesions. It will use immunohistochemical, biochemical and morphologic techniques to correlate motility, cell shape changes and cell surface markers with the cytoskeleton of malignant and benign melanocytes. The findings will be correlated with documented behavior of malignant melanoma in patients diagnosed and followed in the Pigmented Lesion Clinic (PLC) at the Massachusetts General Hospital with the long term goal of improved prognostication and surgical management. There will be five phases of research: 1) immunofluorescent localization of actin, myosin, alpha-actinin, vinculin and tubulin in paraffin and cryostat tissue sections; 2) two-dimensional gel electrophoresis of extracted cytoskeletons with analysis of actin isoforms; 3) development of explant and "tissue blot" cultures for the evaluation of migration rates, shape, surface markers, and cytoskeleton localization in cells of the RGP, VGP, and metastatic melanoma as compared to cells of benign and dysplastic nevi; 4) cytoskeletal whole mount preparations and immunoelectron microscopic localization of alpha-actinin and vinculin; 5) correlation of migration rates, shape, surface markers and cytoskeleton distribution with retrospective and prospective studies in patients from the PLC to determine which factors are predictive of metastatic behavior.